JavaScript provides the user with five arithmetic operators: +, -, *, / and %. The operators are for addition, subtraction, multiplication, division and remainder respectively.
Addition
Syntax
a + b
Usage
2 + 3 // returns 5
true + 2 // interprets true as 1 and returns 3
false + 5 // interprets false as 0 and returns 5
true + "bar" // concatenates the boolean value and returns "truebar"
5 + "foo" // concatenates the string and the number and returns "5foo"
"foo" + "bar" // concatenates the strings and returns "foobar"Hint: There is a handy increment operator that is a great shortcut when you're adding numbers by 1.
Subtraction
Syntax
a - b
Usage
2 - 3 // returns -1
3 - 2 // returns 1
false - 5 // interprets false as 0 and returns -5
true + 3 // interprets true as 1 and returns 4
5 + "foo" // returns NaN (Not a Number)Hint: There is a handy decrement operator that is a great shortcut when you're subtracting numbers by 1.
Multiplication
Syntax
a * b
Usage
2 * 3 // returns 6
3 * -2 // returns -6
false * 5 // interprets false as 0 and returns 0
true * 3 // interprets true as 1 and returns 3
5 * "foo" // returns NaN (Not a Number)
Infinity * 0 // returns NaN
Infinity * Infinity // returns InfinityDivision
Syntax
a / b
Usage
3 / 2 // returns 1.5
3.0 / 2/0 // returns 1.5
3 / 0 // returns Infinity
3.0 / 0.0 // returns Infinity
-3 / 0 // returns -Infinity
false / 5 // interprets false as 0 and returns 0
true / 2 // interprets true a 1 and returns 0.5
5 + "foo" // returns NaN (Not a Number)
Infinity / Infinity // returns NaNRemainder
Syntax
a % b
Usage
3 % 2 // returns 1
true % 5 // interprets true as 1 and returns 1
false % 4 // interprets false as 0 and returns 0
3 % "bar" // returns NaN!Important! As you can see, you cannot perform any sort of operations on Infinity.
Source: The amazing MDN.